I'd separate things we want to do on every query - like case folding, etc. - from things we may only want to do on some queries, e.g. low-result queries. Not sure where inter-wiki search falls - it can be both...
Topic on Talk:Wikimedia Discovery/So Many Search Options
I tried to capture that in the "initial criteria". Things we do for every query are "automatic" and things that are only for some queries have specific initial criteria. I like having everything in one place to keep it all in mind, even though at the moment I don't think the language analysis interacts with anything else.